Administration of several doses of MIF-I or alpha-MSH did not modify colonic temperature or the level of motor activity of rats in ambient temperatures of 4° or 20°C. However, the thermoregulatory but not motor effects of the interaction between MIF-I or alpha-MSH with d-amphetamine were dependent upon ambient temperature. At 4°C, 1.0 mg/kg of both peptides enhanced the d-amphetamine-induced hypothermia, but at 20°C both peptides blocked the hyperthermic effects of d-amphetamine. The hypothermic effect of chlorpromazine (CPZ) at 4°C and 20°C was blocked by 1.0 mg/kg MIF-I but not by 1.0 mg/kg alpha-MSH. No linear dose response relationships between various doses of MIF-I or alpha-MSH and thermal responses were found. Administration of melanin or the use of hypophysectomized rats did not alter the significant interactions observed after peripheral injections.
Bibliographical noteFunding Information:
Supported in part by the Medical Research Service of the Veterans Administration, NIH (NS 07664), and The American Parkinson Disease Foundation. The authors appreciate the help of Debra B. Lazarus in typing the manuscript.
- Ambient temperature
- Drug interaction